Dishwasher having means for collecting and removing food soil

ABSTRACT

An automatic dishwashing machine is provided with a washing liquid filter filtering means in combination with a soilcollecting receptacle located in the machine&#39;&#39;s dishwashing chamber whereby particles of food soil suspended in the recirculated washing liquid within the chamber are collected during washing liquid recirculation and then flushed out of the machine during the wash chamber drainage operation.

United States Patent [191 Cushing et al.

[451 Apr. 30, 1974 DISHWASHER HAVING MEANS FOR COLLECTING AND REMOVING FOOD SOIL Inventors: Donald S. Cushing; Thomas E.

Jenkins, both of Louisville, Ky.

Assignee: General Electric Company,

Louisville, Ky.

Filed: May 12, 1972 Appl. No.: 252,543-

us. C1. 134/104, 210/411 Int. Cl B08b 3/02 Field of Search 134/104, 111; 210/411 References Cited UNITED STATES PATENTS Meeker et a1 134/111 3,122,148 2/1964 Alabaster 134/111 X 3,129,711 4/1964 Schmitt-Matzen 134/111 X 3,542,594 11/1970 Smith et a1 134/104 UX 3,669.132 6/1972 Mamrose 134/104 X $732,877 5/1973 Kloeg 134/104 X Primary Examiner-Robert L. Bleutge Attorney, Agent, or FirmFrancis l-l. Boos, Jr.

[ ABSIRACT An automatic dishwashing machine is provided with a washing liquid filter filtering means in combination with a soil-collecting receptacle located in the machines dishwashing chamber whereby particles of food soil suspended in the recirculated washing liquid within the chamber are collected during washing liquid recirculation and then flushed out of the machine during the wash chamber drainage operation.

12 Claims, 5 Drawing Figures PATENTEBAPR so 1914 saw 2 BF 2 F'iG.S

BACKGROUND OF THE INVENTION The domestic automatic dishwasher is generally of the type having a washing chamber with openframework racks therein for holding dishes to be washed and means for recirculating washing liquid accumulatedin the lower end of the washing chamber upwardly over the dishes to loosen and carry away food soil therefrom. An inherent problem in such a machine is that food soil particles are suspended in the recirculating flow of washing liquid and that redeposition of these particles on the clean dishes can occur during the cleaning process. During the recirculation of the washing liquid large food particles flushed fromthe dishes will be carried downwardly and broken up into particularly small particles that are then washed back on to the dishes. These small particles adhere to the cleaned items and often defy removal during subsequent rinsing steps in the operation of the machine.

An approach to correcting this problem has been to provide a means to remove food particles from the recirculating flow so that the washing liquid moving downwardly in the washing chamber carries food soil with it but the same washing liquid redistributed upwardly in the washing chamber is relatively free of these soil particles. To accomplish this a filtering medium in the form of a screen has been interposed in the path of the liquid recirculation whereby soil particles are prevented from further passage while washing liquid is freeto move therethrough and be recirculated in the machines washing chamber. The use of a filtering screen introduces its own problem; that of the need for cleaning the collected soil from the screen either between each use of the dishwasher or between wash and rinse steps of the operational cycle so that the screen does not become clogged and thereafter prevent passage of liquid therethrough.

One approach to the filter-cleaning problem has been to provide a removable filter that the machine operator can take out of the machine, rinse in the sink, and then reinstall in the machine for further use. Another and more popular approach has been the provision of a selfcleaning filter wherein the filter is flushed by a reversed flow or an automatic filter rinsing step provided in the operational cycle of the machine. A notable example of a diswashing machine having a self-cleaning filtering arrangement is disclosed in U.S. Pat. No. 2,629,391 issued to F. S. Hummel on Feb. 24, 1953. I-Iummel' teaches the provision of a filtering screen disposed over the sump in the bottom of a dishwashing machines wash chamber. He also teaches the use of a specific liquid injection step to flush soil from the filter and also to wash collected soil from the sump and outwardly through a gravity drain line.

More recent examples of self-cleaning filter arrangements in dishwashers will be found in U.S. Pat. No. 3,090,391 issued to H. J. Kaldenberg et al. on May 21, 1963 and U.S. Pat. No. 3,575,185 issued to D. J. Barbulesco on Apr. 20, 1971. The Kaldenberg et al. and Barbulesco patents relate to dishwashing machines utilizing an annular sump arrangement provided circumjacent the axial flow pumping mechanism in a dishwasher and having an annular screen filter arrangement disposed in close proximity to the sump. Each of these patents teaches a different structure for a means for slinging liquid outwardly toward the annular filter whereby a backwash is accomplished to remove soil particles therefrom.

The present invention comprehends the provision of an improved self-cleaning filter arrangement in a dishwashing machine in combination with a soil receptacle preferably disposed at a position remote from the wash chambers sump and adapted to be automatically cleaned during the operation of the machine. The preferred general structure of this invention is adaptable for use with a dishwasher having an axial flow pumping mechanism or various other pumping arrangements.

SUMMARY OF THE INVENTION The present invention may be broadly summarized as relating to an automatic dishwashing machine of the type having a washing chamber with a drainage sump in the bottom wall thereof and means therewith for providing washing liquid in the washing chamber and accumulating it at a relatively low level therein. The washi ng machine includes a means for circulating the flow of washing liquid generally throughout the washing chamber, and a drainage sump is provided in the bottom wall of the chamber for conducting soil-laden washing liquid or effluent out of the machine. A soilcollecting receptacle or trough is provided in the wash chamber and has an open side preferably above the level of accumulated liquid in the chamber and in the path of liquid circulated within the chamber. Adjacent the soil-collecting receptacle is a fine-mesh screen filter disposed across the flow of liquid recirculation and adapted to pass liquid therethrough while blocking the passage of food soil particles. The filtering screen is situated so that its collecting side is disposed toward the aforementioned collecting receptacle. The other side of the screen filter is contacted by some of the recirculating flow of liquid whereby the soil particles collected on its back side are flushed into the collecting receptacle. The invention further includes means for draining particles from the receptacle and into a hopper where they are washed out of the machine, including alternative methods and preferred associated struc ture for creating a pressure differential in the hopper whereby a pressurized evacuation action occurs to empty the hopper of collected soil.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational cut-away view of the bottom portion of a domestic automatic dishwashing machine in accordance with the present invention;

FIG. 2 is a fragmentary sectional view taken along lines 2-2 of FIG. 1;

FIG. 3 is a view taken along lines 3-3 of FIG. 2;

FIG. 4 is a view in vertical section taken along lines 4-4 of FIG. 2; and

FIG. 5 is an alternate structural arrangement for accomplishing the general function of the structure first shown in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is illustrated the lower portion of an automatic dishwashing machine 10 including a cabinet 11 defining therein a washing chamber 12. Access to the washing chamber 12 is obtained by opening a door 13 pivoted at its lower end and located on the front side of the cabinet 11. A dish rack 14 is shown supported for slidable movement within the washing chamber 12 so that it may be selectively slid outwardly through the cabinets front access opening to facilitate loading and unloading of the items to be washed in the machine 10. The lower end of the washing chamber 12 is defined by a bottom wall or floor portion 15 that separates it from a lower motor-pump compartment 16. Housed within the compartment 16 is a motor-pump assembly 17 including an electric motor 18 that drives a pump means 19 for recirculating washing liquid to and from the washing chamber 12 and for draining washing liquid from the washing chamber 12 outwardly to the household sewage system.

The operational cycle of such a machine generally includes a number of washing and rinsing steps and a final drying step. In a dishwasher machine, such as that shown in FIG. 1, heated water from the household supply line is directed into the washing chamber 12 by valve means actuated by a timer control (not shown). The water accumulates to a predetermined level on the floor portion 15 and then the timer control of the machine causes the electric motor 18 to be energized to drive the pump 19 in a recirculation operation. In the recirculation operation the accumulated washing liquid is drained out of the washing chamber 12 by means of a sump 20 emptying into a conduit 21 leading to the pump 19. The liquid is then forced upwardly by the pump 19 through a conduit 22 leading to a hollow horizontally elongated spray arm 25 located within the lower portion of the washing chamber 12.

Generally, clean water is introduced into the machine for each wash step and again for each rinse step, and detergent is added, by automatic means (not shown), for the wash step. The term washing liquid is therefore used herein in a generic sense to refer broadly to any form of cleansing liquid utilized for recirculation within the dishwashing machine. The washing liquid is distributed from the spray arm 25 by means of orifices 26 spaced therealong. along. The spray arm 25 is reactively driven by having at least one of the orifices disposed to discharge a jet stream in a direction such that the spray arm reacts to the force of the discharge and rotates in a horizontal plane. A thorough and generally uniform distribution of washing liquid in the washing chamber 12 is thereby obtained. Recirculation of the washing liquid from the washing chamber 12, through the pump 19 and, thence through the spray arm 25, is continued for a predetermined length of time after which the electrical circuit to the motor 18 is automatically interrupted to halt the pumping action. Thereafter, a drain valve means (not shown) is automatically switched such that an outlet within the pump means 19 for recirculated washing liquid is closed and a drain line outlet is opened. The motor 18 is then reenergized whereby the pump 19 pumps the washing liquid from the washing chamber 12 and outwardly through a drain hose 27 leading ultimately to the household sewage system.

Shown in FIG. 1, and more specifically in FIGS. 2-4, is a soil-removal means in the form of a receptacle 30 having a trough 31 disposed in the path of recirculation of liquid within the washing chamber 12 and adapted to fill and overflow with the recirculated liquid caught therein. The soil-removal means further includes a filtering means 32 contiguous to the trough 31 and disposed in the path of the liquid overflow whereby liquid from the receptacle passes through the screen while soil particles carried in the washing liquid are blocked from passageand therefore halt against the back side of the screen. As shown in FIG. 2, the trough 31 may be transversely elongated to extend across a back wall 34 of chamber 12. In addition to the trough 31, the receptacle 30 further comprises a lower end portion in the form of a tubular box or hopper 35. The trough 31 has a configuration such that liquid collected therein will flow centrally downwardly through an opening 36 (see FIG. 5) into the hopper 35. A bottom 33a of the trough 31 is sloped centrally downwardly, as shown in FIG. 2, and a back wall portion 33b, as shown in FIG. 1, is sloped inwardly whereby liquid collected in the trough will flow toward the central bottom opening 36 thereof. The side of the trough 31 facing toward the wash chamber 12 has an erect wall portion 330 that extends upwardly to the lower edge of the filtering screen 32. The filtering screen 32 is disposed at approximately a 45 angle with reference to the back wall 34 of the wash chamber 12, and the upper long edge of the filtering screen 32 abuts against the forward edge of a horizontally disposed perforated cover plate 37. The cover plate 37 is disposed across the troughs opening and is provided with a uniform arrangement of apertures 38 equidistantly spaced thereacross, as shown in FIG. 3. Successive longitudinally oriented slots 39 are also provided in the cover plate 37.

In the operation of the dishwasher 10 shown in FIG. 1 the washing step of the operational cycle commences with the introduction of water to the washing chamber 12 whereby water accumulates on the floor portion 15 to a maximum level below the under surface of the spray arm 25. Detergent is automatically added to the water and the resultant washing liquid is caused to follow a circular path down the sump 20 and through the conduit 21 to the pump 19. As heretofore described, motor 18 causes the pump 19 to force the washing liquid upwardly and outwardly through the hollow spray arm 25. The spray arm 25 rotates in response to a jet streamdischarged from at least one end thereof and the orifices 26 discharge streams of washing liquid upwardly over items stored in the rack 14 and generally over additional items in one or more other vertically spaced racks (not shown). The cascade of washing liquid distributed throughout the washing chamber 12 tends to progress downwardly over the items in the rack but primarily down along the inside surface of the door 13, the side walls of the wash chamber 12 and the back wall 34. Therefore, the back wall 34 serves as a shedding surface for directing recirculated washing liquid downwardly against the cover plate 37.

As the washing step (or rinsing step) progresses for its predetermined time, the soil-laden washing liquid flows downwardly repeatedly along the washing chamber back wall 34 toward the cover plate 37. Much of the washing liquid moves through the slots 39 and the perforations 38 of the cover plate 37 and into the trough 31. Obviously, once the trough 31 is initially filled, it flows over its forward wall 330 and outwardly through the filtering screen 32. The filtering screen 32 is preferably of a fine mesh whereby even very small food soil particles will be blocked from passage therethrough and retained by the back side of the filtering screen 32. The filtering screen 32 is disposed whereby washing liquid moving down behind the rack 14 and forward of the back wall 34 will strike against the outside surface of the screen. The force of the downwardly cascading washing liquid impinging against the outside surface of the screen 32 serves to jar soil loose from the back side of the screen 32 whereby it will continuously move away from the screen as it collects thereagainst to keep the screen open for passage of washing liquid therethrough. As quantities of soil particles retained in the trough 31 by the screen 32 increase and agglomerate, they tend to precipitate and settle downwardly into the tubular hopper 35 so that by the end of the wash step of the machines operational cycle a high percentage of suspended soil particles have thus been removed from the recirculated washing liquid in the wash chamber 12 and collected in the hopper 35.

At the end of the washing step, the timer-control means (not shown) de-energizes the motor 18 for a brief period to permit final drainage of liquid from the cleaned items in the chamber 12. Thereafter, a valve means within the pump 19 (not shown is switched from a first to a second position in preparation for draining the accumulated washing liquid from the lower end of the wash chamber 12. After the drain valve is automatically positioned in the pump 19, the motor 18 is reenergized whereby the pump 19 receives the washing liquid from the chamber 12 through the sump 20 and the conduit 21 and pumps it'outwardly through the drain line 27 to the lower end of the hopper 35. The drainage flow or effluent is pumped through the hopper and outwardly through a final discharge line 44 draining outwardly from the dishwasher 10. The final dis into the area 51, a lower end opening 52 serves as an entry for chamber 12 effluent pumped from the sump 20, and a side opening 53 permits discharge of effluent from the area51. At the end of the washing step in the operational cycle of the dishwashing machine 10, the motor-pump assembly 17 automatically pumps the washing liquid from the wash chamber 12 through the drain line 27 and thence through the hopper 35 and outwardly through the final discharge line 44. The hopper 35 in FIG. 4 is provided with an elongated vertically reciprocal valve stem 55 having a lower end valve member or annular seal 56 and an upper end annular valve member or seal 57. When the effluent flow from the pump 19 progresses through the drain line 27 the pressurized flow exerts a force upwardly against the valve member 56 whereby the valve stem 55 is raised upwardly. The annular seal 57 is thereby moved into the dotted line position shown in FlG..4 whereby it forms a liquid-tight seal against an O-ring 58. A spring means 59 is provided for normally urging the valve stem 55 downwardly whereby the annular seal 56 closes over the opening 52. This spring is designed to yield in response to incoming flow from the drain line 27. The incoming effluent flow progresses upwardly along the lower endof the valve stem 55 through the valve stem support structure and into the area 51. The pressurized flow fills the area 51 and progresses outwardly through the discharge opening 53. The force of the flow causes a one-way valve member 60 to deflect outwardly whereby the effluent flow, including the collected soil particles from the area 51, are discharged out of the machine through the final discharge line 44.

During the washing step of the operational cycle of the machine, the valve stem 55 is in its downward position, as shown in FIG. 4, whereby the opening 36 permits collected soil from the trough 31 to precipitate downwardly into the hopper 35 and occupy area 51. It will be noted that a flapper valve 65 in the trough 31 is arranged to be normally closed during the washing (or rinsing) step of the machines operational cycle whereby it covers over a trough drain opening 66 in the forward wall 33c of the trough 31. The flapper valve 65 serves as a means for independently draining the trough when the hopper is being drained and comprises a valve seal portion 67 normally contiguous to the inside surface of the wall 330 over the opening 66, and a rearwardly extending integral leg portion 68 that projects over an upwardly extended nose portion 69 of the valve stem 55. When the valve stem 55 is caused to move upwardly by the effluent flow entering the area 51 of the hopper 35, the nose portion 69 contacts the valve leg portion 68 and urges it to swing upwardly whereby the seal portion 67 is swung away from the opening 66. Therefore, during the effluent drainage operation of the machine 10, when the annular seal 57 closes off the opening 36 in the hopper 35, the opening 66 permits final drainage of any residual washing liquid from the trough 33 into the sump 20.

By provision of means, as heretofore described, for sealing off the hopper 35 from the trough 31 during drainage pumpout, a relatively high-pressure condition is established in the area 51 due to the force of the incoming effluent pressurized by the pump 19. This has proven to be a very efficient method of attaining thorough washout of the hopper 35 of all collected soil particles-whereby the area 51 is emptied of soil and ready to receive collected soil particles during the next liquid recirculation in the wash chamber 12 of the machine 10.

It should be noted that during the recirculation of liquid in the wash chamber 12, when soil is being collected in the trough 31, the valve stem 55 is in the downward position, as shown in FIG. 4, whereby the opening 36 permits soil particles to move downward into the area 51 in response to gravity. At this time, the annular seal 56 is disposed across the opening 52 to prevent any leakage of anysoiled liquid back through the line 27, and the valve member 60 is disposed across the opening 53 until liquid pressure thereagainst causes it to open. The valve member 60 thus serves as a gate to prevent drainage backflow into the machine in a situation wherein the household sewage system is temporarily clogged whereby it will not accept the effluent drainage flow from the dishwashing machine.

Referring now to FIG. 5, it will be seen that the soilremoval means shown in the dishwasher 10 may alternatively include a hopper 35 adapted to flush soil particles therefrom without the inclusion of specific me chanical structure and moving parts as described in reference to FIG. 4. FIG. 5 shows the hopper 35 defining a collecting area 51 that is in open communication at all times with the trough 31 by means of the opening 36. Emptying of the area 51 of liquid and collected soil particles occurs in the FIG. embodiment of the hopper due to a pressure differential created in the area 51 because of the inclusion of a jet pump arrangement in the lower area of the hopper 35. This arrangement includes the provision of a constricted or converging inlet tube 75 in liquid flow communication with the drain line 27 whereby pumped-in effluent increases its velocity as its exits from the inward end 76 of the tube 75, resulting in a drop in pressure between the end 76 and a tube 77 disposed to receive the output of effluent from the tube 75. The weight of the soil-laden liquid collected in the chamber 35, with normal atmospheric pressure bearing downwardly thereagainst, is sufficient to cause the contents of the chamber 35 to move downwardly toward the area of comparatively low pressure resulting at the output end 76 of the tube 75 whereby the area 51 is evacuated of the liquid and the soil carried therewith. In addition, liquid and/or soil in the trough 31 will drain out through the area 51 and outwardly through the discharge line 41 so that the trough is empty and ready for the next recirculation operation in the machine.

We claim:

1. In an automatic dishwashing machine having a wash chamber, means for accumulating washing liquid in the lower portion of the chamber and circulating a flow of washing liquid throughout the chamber, means for draining the liquid from the machine including a sump in the bottom of the chamber, a soil-removal receptacle independent of the sump and disposed in the path of recirculation and adapted to fill and overflow with recirculating liquid, a filtering means disposed in the path of the overflow and adapted to pass liquid from the receptacle and block passage of soil particles therethrough, the receptacle having means therewith to effect drainage thereof at a predetermined time during the operation of the machine, and the filtering means being adapted to be automatically cleaned by the recirculating liquid in the chamber.

2. The invention of claim 1 wherein the filtering means comprises a fine-mesh screen disposed with a rear side thereof across the path of overflow from the receptacle and its front side disposed to be washed by the recirculation flow of liquid striking thereagainst whereby soil particles clinging to the front side are dislodged back toward the receptacle.

3. The invention of claim 1 further including a sump in the bottom of the wash chamber for collecting liquid drainage from the chamber, the sump being in drain flow communication with the collecting receptacle whereby liquid from the sump is merged with the liquid drained from the receptacle and thereafter discharged from the machine, and means in the machine for pressurizing the drain flow discharged therefrom.

4. The invention of claim 1 wherein the means to effect drainage of the receptacle includes means for sealing off a portion of the receptacle from the chamber during the receptacle drainage operation, and the machine having means for draining liquid from the chamber and thence through the sealed-off portion of the receptacle, and means for pressurizing the liquid drainage from the receptacle whereby the liquid pressure in the sealed-off portion of the receptacle during the drainage operation is greater than atmospheric pressure.

5. The invention of claim 1 including means for causing a pressure differential between upper and lower portions of the receptacle during the drainage operation in order to urge collected soil out of the receptacle.

6. The invention of claim 1 wherein the receptacle includes a hopper for receiving and temporarily retaining soil particles.

7. The invention of claim 6 wherein the hopper is provided with means for sealing it off from the washing chamber during the drainage operation of the dishwashing machine.

8. The invention of claim 7 wherein the means for sealing off the hopper is actuated as an incident of drainage flow pumped into the hopper.

9. The invention of claim 1 wherein the receptacle includes a trough portion and a hopper for receiving soil particles from the trough portion, means for sealing off the hopper from the trough portion during drainage of the hopper, and wherein the trough is provided with means for effecting its drainage independently of the hopper while the hopper is being drained.

10. The invention of claim 1 wherein the receptacle is at least partially disposed above the level of washing liquid accumulation on the bottom of the washing chamber.

11. The invention of claim 1 wherein the receptacle drainage means includes structure comprising a jet pump arrangement.

12. In an automatic dishwashing machine of the type having a dishwashing chamber with a drainage sump in the bottom thereof, means for providing washing liquid and accumulating it to a relatively low level in the bottom of the chamber, means for circulating the flow of washing liquid throughout the washing chamber, means for draining the chamber outwardly through the sump, a soil collecting receptacle having an opening into the chamber above the normal level of accumulated liquid in the chamber, the opening being in the path of washing liquid circulated in the chamber, means adjacent the lower end of the receptacle for draining the receptacle, the means for draining the receptacle being in liquid flow communication with the sump, means for pressurizing the drainage flow out of the sump and toward the receptacle drainage means, and means for directing drainage both from the sump and the receptacle outwardly from the dishwashing machine. 

1. In an automatic dishwashing machine having a wash chamber, means for accumulating washing liquid in the lower portion of the chamber and circulating a flow of washing liquid throughout the chamber, means for draining the liquid from the machine including a sump in the bottom of the chamber, a soil-removal receptacle independent of the sump and disposed in the path of recirculation and adapted to fill and overflow with recirculating liquid, a filtering means disposed in the path of the overflow and adapted to pass liquid from the receptacle and block passage of soil particles therethrough, the receptacle having means therewith to effect drainage thereof at a predetermined time during the operation of the machine, and the filtering means being adapted to be automatically cleaned by the recirculating liquid in the chamber.
 2. The invention of claim 1 wherein the filtering means comprises a fine-mesh screen disposed with a rear side thereof across the path of overflow from the receptacle and its front side disposed to be washed by the recirculation flow of liquid striking thereagainst whereby soil particles clinging to the front side are dislodged back toward the receptacle.
 3. The invention of claim 1 further including a sump in the bottom of the wash chamber for collecting liquid drainage from the chamber, the sump being in drain flow communication with the collecting receptacle whereby liquid from the sump is merged with the liquid drained from the receptacle and thereafter discharged from the machine, and means in the machine for pressurizing the drain flow discharged therefrom.
 4. The invention of claim 1 wherein the means to effect drainage of the receptacle includes means for sealing off a portion of the receptacle from the chamber during the receptacle drainage operation, and the machine having means for draining liquid from the chamber and thence through the sealed-off portion of the receptacle, and means for pressurizing the liquid drainage from the receptacle whereby the liquid pressure in the sealed-off portion of the receptacle during the drainage operation is greater than atmospheric pressure.
 5. The invention of claim 1 including means for causing a pressure differential between upper and lower portions of the receptacle during the drainage operation in order to urge collected soil out of the receptacle.
 6. The invention of claim 1 wherein the receptacle includes a hopper for receiving and temporarily retaining soil particles.
 7. The invention of claim 6 wherein the hopper is provided with means for sealing it off from the washing chamber during the drainage operation of the dishwashing machine.
 8. The invention of claim 7 wherein the means for sealing off the hopper is actuated as an incident of drainage flow pumped into the hopper.
 9. The invention of claim 1 wherein the receptacle includes a trough portion and a hopper for receiving soil particles from the trough portion, means for sealing off the hopper from the trough portion during drainage of the hopper, and wherein the trough is provided with means for effecting its drainage independently of the hopper while the hopper is being drained.
 10. The invention of claim 1 wherein the receptacle is at least partially disposed above the level of washing liquid accumulation on the bottom of the washing chamber.
 11. The invention of claim 1 wherein the receptacle drainage means includes structure comprising a jet pump arrangement.
 12. In an automatic dishwashing machine of the type having a dishwashing chamber with a drainage sump in the bottom thereof, means for providing washing liquid and accumulating it to a relatively low level in the bottom of the chamber, means for circulating the flow of washing liquid throughout the washing chamber, means for draining the chamber outwardly through the sump, a soil collecting receptacle having an opening into the chamber above the normal level of accumulated liquid in the chamber, the opening being in the path of washing liquid circulated in the chamber, means adjacent the lower end of the receptacle for draining the receptacle, the means for draining the receptacle being in liquid flow communication with the sump, means for pressurizing the drainage flow out of the sump and toward the receptacle drainage means, and means for directing drainage both from the sump and the receptacle outwardly from the dishwashing machine. 